The potential impact of new TB vaccines on the burden of TB in people living with HIV in South Africa.

Background: People living with HIV (PLHIV) are at increased risk of tuberculosis (TB). New TB vaccines may help reduce this burden. New TB vaccine candidates are safe and immunogenic in PLHIV.There is currently limited data on vaccine efficacy in this population.

Methods: Using mathematical modelling we explored the potential impact of a novel TB vaccine on TB burden in PLHIV in South Africa between 2030-2050. We compared the impact of a vaccine delivered irrespective of HIV status to vaccination of either PLHIV or people without HIV. We explored the impact of reduced vaccine efficacy and duration of protection in PLHIV relative to people without HIV on our model predictions.

Results: Vaccination irrespective of HIV status, with a vaccine with equal efficacy and duration in PLHIV, could avert up to 1.01 (95% range: 0.96-1.22) million TB cases in PLHIV. Restricting vaccination to PLHIV or people without HIV would achieve 65% (60-70) and 48% (46-53) of the total impact respectively. These results are strongly dependent on the assumed efficacy and duration of protection in PLHIV. Further information on these characteristics is important to identify the most efficient use of new vaccines to reduce TB burden in PLHIV.

Conclusions: Our results suggest that new vaccines could play an important role in reducing the TB burden in PLHIV. Vaccines targeted at people without HIV individuals could provide significant indirect benefit to PLHIV, but vaccines which are safe and effective in PLHIV will be critical to maximizing the impact in this population.